1. Field of the Invention
This invention relates to a key operation type locking device used in a lid for opening and shutting a box such as, for example, an automobile glove compartment.
2. Description of the Prior Art
The locking devices of this class heretofore known to the art include those which are disclosed in Japanese Utility Model Public Disclosure No. 60-162663, No. 63-78670 and No. 1-151571 and Japanese Patent Public Disclosure No. 61-130576, for example.
Though these conventional locking devices are more or less different in construction from one another, they basically comprise a frame provided with a cylinder lock to be fixed in the lid of a glove compartment, an opening-shutting knob pivotally supported on the front surface side of the frame, a storing (or retaining) part formed on the rear surface side of the frame and adapted to store therein a striker disposed on the compartment side, a locking member disposed vertically movably or rotatably and adapted to open or shut the opening of the storing part, an operating lever adapted to urge the locking member to move and provided on one terminal part thereof with a connecting hole, and an eccentric shaft disposed on the rear terminal of the cylinder lock and inserted idly inside the connecting hole, whereby the interlock of the rotation of the cylinder lock with the motion of the operating lever enables the other terminal part of the operating lever to be moved between a position at which the operating lever interferes with a depressing claw part disposed on the rear side of the opening-shutting knob and a position at which the interference is not produced.
When the key for initiating actual use of the locking device is operated so as to rotate the cylinder lock in the unlocking direction, the other terminal part of the operating lever is moved to the position in which it interferes with the depressing claw part of the opening-shutting knob, the opening-shutting knob is lifted against the resilient pressure which tends to return the opening-shutting knob to its home position, and the depressing claw part of the knob is caused to depress the other terminal part of the operating lever downwardly. This depression of the other terminal part side of the operating lever causes the locking member to move in a direction to open the storing part, effects automatic release of the locking state of the striker inside the storing part, and consequently allows release of the lid from the glove compartment.
When the cylinder lock is rotated in the locking direction, the other terminal part of the operating lever moves to the position in which it does not interfere with the depressing claw part of the opening-shutting knob, and the depressing claw part of the knob simply swings idly even if the opening-shutting knob in that state of the locking device is pulled up time and again. Thus, the lid is allowed to remain infallibly in the closed state.
In the conventional locking device utilizing this operating principle, however, since the operating lever which fulfills the role of keeping the locking device in the locked or unlocked state is formed of metallic material as a one-piece component and has one terminal part thereof simply inserted idly in the eccentric shaft of the cylinder lock through the connecting hole, it is necessary to provide a mechanism, such as a push-on fixing member (e.g. a washer) for preventing the one terminal part side of the operating lever from falling off the cylinder lock side.
The conventional locking device, therefore, not only makes assembly of the metallic operating lever troublesome but also inevitably results in an increase in the number of component parts and further requires the metallic operating lever to be subjected to a rustproofing surface treatment. This point constitutes one factor in the increased cost of production and possibly causes weight to be added to the device.
Further, for the purpose of preventing the opening-shutting knob from producing unwanted backlash and resiliently urging the opening-shutting knob to the home position, the conventional locking device adopts a constriction in which a double-torsion spring is mounted on the supporting shaft which serves to support the opening-shutting knob pivotally on the frame so that the resilient pressure of the double-torsion spring will urge the opening-shutting knob to the home position. The use of the double-torsion spring of this nature is advantageous in that this spring is capable of infallibly during the opening-shutting knob to the home position. In contrast, the work involved in attaching this opening-shutting knob to the frame is inefficient because the double-torsion spring must be attached to the supporting shaft and, at the same time, the opening-shutting knob must be attached to the frame, while the supporting shaft must e inserted through the bearing on the opening-shutting knob side and the bearing on the frame side.
The main object of this invention is to provide an improved locking device which is capable of effectively solving the problems of the conventional locking device described above.